Emergency swing-reversing control for cranes and other horizontally swinging load handling apparatus



' June 21, 1966 M. LAHARTY 3,256,998

EMERGENCY SWING-REVERSING CONTROL FOR CRANES AND OTHER HORIZONTALLY SWINGING LOAD HANDLING APPARATUS I Filed Jan. 18, 1965 2 Sheets-Sheet 1 I! III JJJ/l/IIIII M170 L. Lahariy INVENTOR. :E

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June 21, 1966 M. LAHARTY 3,

EMERGENCY SWING-REVERSING CONTROL FOR CRANES AND OTHER HORIZONTALLY SWINGING LOAD HANDLING APPARATUS Filed Jan. 18, 1965 2 Sheets-Sheet. 2

I31 Li Milo LLaharfy INVENTOR.

United States Patent 3 256 998 EMERGENCY SWING-lREXERSING CONTROL FOR CRANES AND OTHER HORIZONTALLY SWING- ING LOAD HANDLING APPARATUS Milo L. Laharty, Roseburg, Oreg., assignor to Forrest Industries, Inc., Dillard, Oreg. a corporation of Oregon Filed Jan. 18, 1965, Ser. No. 426,060 8 Claims. (Cl. 21239) 'of the apparatus cannot see to the rear and is intent upon handling a load supported on a forwardly extending boom, the avoidance of such accidents is difficult and a constant source of worry.' Moreover it detracts materially from the skillful performance of the'operators duties. It is the general object of the present invention to provide an emergency swing-reversing control for cranes,

shovels and like load handling apparatus which will sense the presence of a person standing to the rear of the apparatus in a location where he may be injured and which will reverse the swinging motion of the apparatus substantially instantaneously, thereby avoiding injuring the person.

Further objects of the present invention are the provision of an emergency swing-reversing control for cranes and the like, which control is applicable to the conventional shift and drive mechanism of the crane without substantial modification thereof; which instantaneously reverses the swinging movement of the crane; which is reliable in its operation; which is simple and inexpensive to install; and which easily is adjustable both as to the extent of the protected area and the degree of reverse motion achieved.

The swing reversing control of my invention is broadly applicable to cranes, shovels or other machines which are controlled hydraulically, manually or with steam; Such apparatus is characterized by having a body pivoted for horizontal swinging movement. Reversible drive means are connected to the body for swinging it in right swing and left swing arcs. Shift means are connected to the drive for adjusting it between right swing, left swing, and neutral operating conditions.

The control of the invention includes at least one substantially horizontal contact lever extending rearwardly and outwardly a predetermined distance from a central point on at least one side, usually both sides, of the body of the apparatus. The lever is'mounted for movement toward and away from the apparatus. Resilient means act on the lever for maintaining it in a position normally away from the apparatus. Link means connect the lever and the shift means of the apparatus for reversing the shift means when the lever is moved toward the apparatus body.

Thus as the rear end of the apparatus sweeps against a person who is standing in the path of its swinging movement, the lever on the side of the apparatus is depressed. This immediately operates the shift mechanism of the apparatus to reverse its swinging motion by a predetermined amount, overriding any force which may be applied to the shift means by the operator in an effort to continue its movement in the forward direction. In this manner the person is saved from serious injury.

Considering the foregoing in greater detail and with particular reference to the drawings, wherein:

3,256,998 Patented June 2l, 1966 ice FIGS. 1 and 2 are schematic plan and side elevational views, respectively, of the body of a crane or shovel illustrating the manner of attachment of the herein described swing-reversing control;

FIG. 3 is a detail vertical section-a1 view, taken along line 3-3 of FIG. 1 and illustrating one manner of mounting the control on the side of the apparatus;

FIG. 4 is a detail View in end elevation illustrating the manner of application of the presently described control to an hydraulically operated swing shifting mechanism for the crane or shovel;

FIG. 5 is a sectional view in side elevation taken along line 55 of FIG. 4;

FIG. 6 is a circuit diagram of the electric circuit employed in the control of FIGS. 4 and 5; and

FIG. 7 is a sectional view illustrating the application of the presently described control to a crane or shovel provided with a mechanical shift, a schematic wiring diagram also being included. I

The manner of installation of the control of the invention to a conventional crane is shown in FIGS. 1 and 2. As usual, the crane consists of a crane body 8 mounted on a turntable 10 supported on track drive 12. An arm 14 with conventional rigging 16 extends forwardly from the body. A counterweight 18 extends rearwardly from the body.

The operators station is located forwardly on the body where he is afforded a clear view of arm 14 and the work being handled. However, the area behind the crane is concealed from him. It includes the area swept by the rear portion of the crane body as it swings from right to left, particularly evident in FIG. 1. A person standing in this area is likely to be crushed against any obstruction which may be present in it.

To safeguard against this contingency at least one side, preferably both sides, of the body are provided with substantially horizontal contact lever means indicated generally at 20, 22. These are arranged to sweep the danger area behind the crane body. When one of them contacts a solid object such as the body of a bystander, it is depressed and actuates through a suitable linkage the shifting mechanism of the crane, reversing it so that injury to the bystander is prevented.

As shown in FIG. 2, lever means 20 preferably has a gate-shaped construction covering a substantial vertical area. It includes a top lever arm 24, a bottom lever arm 26, a cross piece 28 and a diagonal brace 30.

The lever assembly extends rearwardly a predetermined distance and outwardly at a predetermined angle from a central point on the body at which is located a bracket support 32. A vertical shaft 34 is journaledin bearings 36 contained in the bracket. The inner ends of lever arms 24, 26 are fixed to the ends of this shaft, as appears in FIG. 3.

Vertical shaft 34 mounts a radial contact pin 38, the purpose of which will appear hereinafter. It also mounts a coil spring 40 arranged in such a manner as to provide resilient means acting on the lever arms for maintaining them in a position normally away from the crane body.

Accordingly the upper end of spring 40 is anchored on a radial post 42 extending outwardly from shaft 34. The lower end of the spring is anchored in an opening through bracket 32.

Stop means also are provided for limiting the degree of outward rota-tion of lever 20. To this end thereis provided a stop 44, the position of which is adjustable in a slot extending across the top of bracket 32. Post 42 may comprise a mechanical connection, it preferably includes electrically operated elements to insure its sensitivity and rapid response. It thus may be applied to shifts which are fluid controlled, as by means of hydraulic fluid, steam or air, or to shifts which are mechanically operated. Its application to a conventional fluid controlled shift is illustrated in FIGS. 4, 5 and 6.

A rigid, manually operated swing shift lever, not illustrated but analogous to flexible lever 50, is fixed to a rocking cam bar 52 journaled between the side walls of case 54. Fixed to cam bar 52 are a first roller cam 56 and a second roller cam 58.

The rollers of earns 56, 58 bear respectively against plates 60, 62 which are hinged at one end to a support shaft 64. The outer ends of plates 60, 62 bear against the plu-ngers 66, 68 of an hydraulic valving unit 70.

The valving unit is of conventional construction and is fed by conduit 72 with hydraulic fluid under pressure from a central reservoir. When plunger 66 is depressed, the flow of fluid is diverted through conduit 74 to mechanism which swings the crane, for example, to the left. When plunger 68 is depressed, fluid is diverted through conduit 76 to mechanism which swings the crane to the right.

By the present invent-ion there is added to the control described above a superimposed control which is actuated by levers 20, 22 and which in an emergency takes away the manual control normally exerted by the operator, instantaneously reversing the swinging motion of the crane to prevent a possible accident.

To this end there is employed a flexible control lever 50 including an upper segment 80 and a lower segment 82 interconnected through a resiliently deformable segment 84 which may be, for example, a length of stiff coil spring.

Also employed are electric link means connecting together lever 22 and cam bar 52 so that the latter may be moved as necessary to accomplish the desired reversal of the swinging motion of the crane body. The construction and manner of application of the electric link means employed are evident from a consideration of FIGS. 4, 5 and 6.

Mounted inside case 54 are a pair of solenoid thrust units 86, 88. Each of these with its associated mechanism is similar to the other and accordingly solenoid unit 86 alone is illustrated.

The thrust shaft 90 of solenoid 86 mounts an extension 91 divided into two sections having r'everse threads. An adjustment nut 92 is threaded onto the shaft for adjusting the extent of its thrust.

The end of shaft extension 91 is pivotally connected by means of a connector 94 to the shaft of a roller cam 96. The latter is pivoted intermediate its ends on a stationary shaft 98. The roller of the cam bears operatively against one side of swinging bar 60 against the other side of which bears the roller of cam 56.

The construction of the mechanism associated with solenoid unit 88 is similar, there being a roller cam 99, illustrated schematically in FIG. 6 which bears against swinging bar 62, opposing the roller of cam 58.

Limit switch 100 of a pair of limit switches 100, 102 in an electric circuit with solenoids 86, 88 is housed in a post 104, FIG. 3, contained in bracket 32 on the side of the crane body. The post is mounted on a base 106 which adjustably is secured in a slot in the base of the bracket by means of bolts 108. This makes possible adjustment of the position of limit switch 100 with reference to contact pin 38 on vertical shaft 34 which mounts lever 20, determining the sweep of the lever which must occur before energization of the crane reversal mechanism takes place.

As is evident in the circuit diagram of FIG. 6, such reversal occurs when either one of contact levers 20, 22

is depressed, as by striking the body of a person standing in the path of the crane as it swings from side to side.

Assuming the operator has moved operating lever 50 a in a direction such as to cause the crane to swing to the left as viewed in FIG. 1 and that contact lever 20 thereupon is depressed by striking a person who is in the path of the swinging crane, the result will be that limit switch will be closed, energizing solenoid 86. This will actuate roller cam 96 which will rotate swinging bar 60.

Such rotation will have two effects. First of all it shuts off the valve unit controlled by plunger 66, arresting the swinging motion of the crane body to the right. Secondly, by backing off cam 56 it rotates cam bar 52. This actuates cam 58, also fixed to cam bar 52, depressing hinged plate 62 as well as plunger 68 of valve unit 70. This in turn reverses the movement of the crane body, causing it to swing to the right as viewed in FIG. 1 until solenoid 86 comes to the end of its stroke and relieving anyone who may have been in danger.

The foregoing sequence occurs irrespective of the fact that the operator may have been oblivious to the danger and may have continued to move lever 52 in the direction of right swing. The force exerted by solenoid 86 through cam 96 is suflicient to overside the pressure exerted by the operator, since lever 50 flexes at the coil spring joint 84 between its two sections 80, 82.

An alternate form of the invention, in which the control is applied to a mechanically controlled shift for a crane or other swinging apparatus, is illustrated in FIG. 7.

In this form of the invention, the body 8 is provided again with rearwardly and outwardly extending lever units 20, 22. The mechanical swing shift includes an operating lever 110 having upper and lower segments 112, 114 interconnected by a resiliently deformable segment 116 which may comprise a length of stiff coil spring.

Lever 110 is fulcrumed about a pivot pin 118. Its lower end is coupled to one end of a connecting rod 120, the other end of which is connected to a crank 122. The latter in turn is fixed to a shaft 124 which operates the swinging mechanism of the crane in a conventional manner.

To accomplish the purpose of the present invention, the forgoing conventional construction is modified by bolting to connecting rod a plate 126 mounting a contact pin 128.

Connecting rod 120 may be driven in forward and reverse directions independently of pressure exerted by the operator on lever 110, by means of a pair of motors 130, 132 having mounted on their shafts reels 134, 136, respectively, upon which are wound cables 138, 140. The ends of the cables are fixed adjustably to opposite sides of plate 126. Accordingly, as one or the other of the cables is wound up on its reel, connecting rod 120 is moved in one direction or the other, thereby shifting the swinging drive mechanism of the crane into reverse.

Energization of one or the other of motors 130, 132 is accomplished by means of an electric circuit, also illustrated in FIG. 7. Normally open limit switches 142, 144 corresponding to limit switches 100, 102 of the embodiment of FIG. 6, are located on the crane body in working relation to levers 20, 22 respectively. Normally closed limit switches 146, 148 are located so that they may be actuated by the movement of pin 128 on plate 126.

Also included in the circuit are a pair of horns or other sound making devices 150, 152.

The operation of the FIG. 7 form of the invention is as follows:

When lever 20 is depressed by contact with a bystander during swinging operation of the crane, switch 142 is closed. This closes the circuit including horn 150, normally closed switch 146, and motor 130.

The motor thereupon drives reel 134 pulling on cable 138. This moves connecting rod 120 to the left as viewed in FIG. 7, and reverses the swinging movement of the crane, even against pressure exerted manually by the operator on lever 110, which flexes at joint 116.

Movement of connecting rod 120 continuesuntil contact pin 128 strikes normally closed switch 146, opening it and breaking the circuit. Motor 130 thereupon is stopped, arresting the reverse swinging motion of the crane and permitting the operator to continue its normal operation.

It accordingly will be seen that there is provided an apparatus in which the several objects of this invention are achieved and which is well adapted to meet the conditions of practical use.

It is to 'be understood that the form of my invention herein shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoin-ed claims.

Having thus described my invention, I claim:

1. In load handling apparatus having a body pivoted forhon'ozntal swinging movement, reversible swing drive means connected to the body, and shift means connected to the drive means for adjusting the drive means between right swing, left swing, and neutral operating conditions; and emergency-swing reversing control comprising:

(a) substantially horizontal contact lever means extending rearwardly and outwardly a predetermined distance from at least one side of the body,

(b) mounting means mounting the contact lever means for movement toward and away from the body,

(c) resilient means acting on the contact lever means for maintaining it in a position normally away from the body, and

(d) link means connecting together the lever means and shift means for reversing the shift means when the lever means is moved toward the body of the apparatus.

2. The control of claim 1 wherein the link means comprises electrical link means including an electric circuit, a switch in the electric circuit positioned for actuation by the lever means, and solenoid-operated ram means in the electric circuit and positioned adjacent the shift means for altering the same.

3. The control of claim 1 wherein the shift means includes a pivotal cam bar mounting a radially extendingcam and a fluid-operated valve engaged by the cam for operating a fluid control circuit operable to shift the drive means; and wherein the link means comprises electrical means including an electric circuit, an electric switch in the circuit positioned for actuation by the contact lever means, a solenoid in the electric circuit, cam means connected to the solenoid and engaging the bar for reversing the switch means upon energization of the solenoid.

4. The control of claim 1 including a manually operating lever connected to the shift means, the operating lever including a length of stifily resilient material having a stiffness predetermined to permit manual operation of the shift means through the operating lever during normal operation of the apparatus, but to permit overriding of the operating lever and reversal of the shift means upon actuation of the contact lever means.

5. The control of claim 1 including a manually operated lever connected to the shift means, the operating lever including a length of stifily resilient coil spring having a stillness predetermined to permit manual operation of the shift means through the operating lever during normal operation of the apparatus, but to permit overriding of the operating lever and reversal of the shift means upon actuation of the contact lever means.

6. The control of claim 1 wherein the shift means includes a connecting rod interconnecting an operators control lever and a shifting mechanism and having a contacting member thereon; and wherein the link means comprises electrical link means including an electric circuit, a first electric switch positioned for actuation by the contact lever means and operable to make the circuit, a second electric switch in the electric circuit positioned to be contacted by the contact member on the connecting rod-and operable to break the circuit, an electric motor in the circuit, and drum operated cable means driven by the electric motor and connected to the connecting rod for reversing the shift means, upon actuation of the first switch by the contact lever, for a time interval terminated by actuation of the second switch by the contact member on the connecting rod.

7. In load handling apparatus having a body pivoted for horizontal swinging movement, reversible swing drive means connected to the body, and shift means connected to the drive means for adjusting the drive means between right swing, left swing, and neutral operating conditions; an emergency swin-g reversing control comprising:

(a) a pair of vertically spaced lever arms extending rearwardly a predetermined distance and outwardly at a predetermined angle from a central pivot point on at least one side of the body,

(b) a vertical shaft mounting the inner ends of the arms,

(c) journal means journalling the shaft on the side of the body,

(d) resilient means acting on the lever arms for maintaining them in a position normally away from the body, and

(e) link means connecting together the lever arms and the shift meansfor reversing the shift means when the lever arms are moved toward the body.

8. The apparatus of claim 7 wherein the resilient means comprises a coil spring encircling the shaft and having one of its ends anchored thereon with the other end anchored to a stationary frame member, the spring being arranged for maintaining the lever arms in a position normally away from the body.

References Cited by the Examiner UNITED STATES PATENTS 3,168,729 2/1965 Volber-g 21239 X FOREIGN PATENTS 1,149,150 5/1963 Germany.

HUGO o. SCHULZ, Primary Examiner. ARTHUR L. LEVINE, Assistant Examiner. 

1. IN LOAD HANDLING APPARATUS HAVING A BODY PIVOTED FOR HORIZONTAL SWINGING MOVEMENT, REVERSIBLE SWING DRIVE MEANS CONNECTED TO THE BODY, AND SHIFT MEANS CONNECTED TO THE DRIVE MEANS FOR ADJUSTING THE DRIVE MEANS BETWEEN RIGHT SWING, LEFT SWING, AND NEUTRAL OPERATING CONDITIONS; AND EMERGENCY-SWING REVERSING CONTROL COMPRISING: (A) SUBSTANTIALLY HORIZONTAL CONTACT LEVER MEANS EXTENDING REARWARDLY AND OUTWARDLY A PREDETERMINED DISTANCE FROM AT LEAST ONE SIDE OF THE BODY, (B) MOUNTING MEANS MOUNTING THE CONTACT LEVER MEANS FOR MOVEMENT TOWARD AND AWAY FROM THE BODY, (C) RESILIENT MEANS ACTING ON THE CONTACT LEVER MEANS FOR MAINTAINING IT IN A POSITION NORMALLY AWAY FROM THE BODY, AND (D) LINK MEANS CONNECTING TOGETHER THE LEVER MEANS AND SHIFT MEANS FOR REVERSING THE SHIFT MEANS WHEN THE LEVER MEANS IS MOVED TOWARD THE BODY OF THE APPARATUS. 